M2 worldwide is some 80 trillion.
When #Bitcoin has taken over this means one #Bitcoin would be ~ $ 4 million (as a starter).
Now look at the onchain transaction and what that would mean to the value being moved around.
Still think we plebs will transact much on-chain ?
On-chain will be used for large settlements.
High value, and for us, high fees.
Invest some time in LN.
It is working, fast and cheap.
You can be self custodial or not, whatever you like.
You will be using it in the future.